problems with a C script, exiting with signal 10

[Jordi Moles Blanco]

Hi,

i've been trying to debug what you suggested, but no luck so far :(

The thing is that i checked out all the calls to arrays, space handling 
and so on, and i couldn't find anything wrong.

After that, i ended up trying the "hard" way, which is to keep a file 
/tmp/debug.log where the script writes everything that it does. So... 
the problem was that even in those cases when postfix logged a "signal 
10" error, the logs showed that the C script got to the end of the file, 
it executed every single line, it doesn't get stuck manipulating arrays 
or anything like that.


any idea?

Thanks.



En/na Jordi Moles Blanco ha escrit:
> Hi,
>
> thanks for the reply, i will have a close look at what you suggested. 
> The thing is that, yes, i work with arrays, pointers, mallocs and so 
> on. I'll try to make sure everything is initiliazed properly before 
> being used.
>
> Thanks for the advice.
>
>
>
>
> En/na Patrick Mahan ha escrit:
>>
>>
>> Jordi Moles Blanco presented these words - circa 8/7/08 3:13 AM->
>>> Hi,
>>>
>>> I've got this home-made script, written in C, on a  Freebsd 7.0 
>>> server with different versions of postfix: 2.3,2,4 and 2.5
>>>
>>> The problem is that, while most of the time it works like a charm, 
>>> sometimes it crashes and bounces the message. It's not really a big 
>>> deal, cause the sender gets notified that their mail wasn't 
>>> delivered and hopefully, they will resend it. However, the problem 
>>> is that I've tried to debug my script but found nothing wrong at 
>>> all, cause it only fails from time to time, let's say... once for 
>>> each 2000 messages that postfix receives, and it appears to do so in 
>>> a random way.
>>>
>>> As i said... postfix can fail to deliver a message to one particular 
>>> mailbox, but if then you resend the very same message to the very 
>>> same mailbox, it will be delivered.
>>>
>>> The error is reported in both "maillog" and "messages", like this:
>>>
>>>
>>> ******/var/log/maillog********
>>> Aug  7 01:55:19 mail01 postfix/pipe[27534]: 3E1A0143709: 
>>> to=<EMAIL_ACCOUNT>, relay=quota_postfix, delay=0.23, 
>>> delays=0.11/0/0/0.11, dsn=5.3.0, status=bounced (Command died with 
>>> signal 10: "/usr/local/etc/postfix/quota_postfix")
>>>
>>>
>>> *****/var/log/messages*******
>>> Aug  7 01:55:19 mail01 kernel: pid 29535 (quota_postfix), uid 125: 
>>> exited on signal 10
>>>
>>
>> Well signal 10 is SIGBUS which is indicative of (generally) a bad 
>> address,
>> non-aligned memory address (on platforms it matters) or a hardware 
>> error.
>> I would look for places you are dereferencing a pointer without perhaps
>> first validating it.
>>
>> Given that it rarely occurs, I might suspect that you are allocating 
>> some
>> memory, but failing to completely initialize (malloc() doesn't zero out
>> memory) it or assuming it is already initialize.
>>
>> Good luck,
>>
>> Patrick
>>>
>>> Here you have some extra information about the script itself and the 
>>> master.cf
>>>
>>>
>>> *****/usr/local/etc/postfix/quota_postfix***
>>>
>>> # ls -la /usr/local/etc/postfix/quota_postfix
>>> -rwsr-xr-x  1 postfix  postfix  20048 Aug  4 10:18 
>>> /usr/local/etc/postfix/quota_postfix
>>>
>>> It's got de suid flag cause it performs a "du" command and other 
>>> file operations which need permissions, although i've tried with 
>>> other groups of permissions and it eventually crashes anyway with 
>>> "signal 10"
>>>
>>> ******master.cf*********
>>>
>>> .........
>>>
>>> # spamfilter
>>> spamfilter      unix    -       n       n       -       20      pipe
>>> flags=R user=filter argv=/home/antispam.pl "localhost:10027" 
>>> "antispam" "${sender}" "${recipient}" "/usr/local/bin/spamc"
>>>
>>> # from spamfilter to smtpd:10026
>>> localhost:10027 inet    n       -       n       -       100       
>>> smtpd -o content_filter=quota_postfix
>>>
>>>
>>> # quota_postfix
>>> quota_postfix      unix    -       n       n       -       20      pipe
>>> flags=R user=filter argv=/usr/local/etc/postfix/quota_postfix 
>>> "localhost" "10028" "${sender}" "${recipient}" "${domain}"
>>>
>>> # from quota_postfix to smtpd:10028
>>> localhost:10028 inet    n       -       n       -       100       
>>> smtpd -o content_filter=
>>>
>>> ................
>>>
>>> So far, any program which crashed would leave a ".core" file in 
>>> /usr/crash, but this one is not doing the same, so... i can't 
>>> actually debug from the core file either.
>>> Sysctl in my FreeBSD server is ok, but i guess that postfix, somehow 
>>> is preventing this filter from generating a core file. Is that 
>>> possible? Or am i completely wrong?
>>>
>>> How could I, at least, generate the .core file?
>>>
>>> Thanks.
>>>
>>>
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>
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